1. Field of Invention
The present invention relates to human telomerase, a ribonucleoprotein enzyme involved in human telomere DNA synthesis. The invention provides methods and compositions relating to the fields of molecular biology, chemistry, pharmacology, and medical and diagnostic technology.
2. Description of Related Disclosures
The DNA at the ends or telomeres of the chromosomes of eukaryotes usually consists of tandemly repeated simple sequences. Telomerase is a ribonucleoprotein enzyme that synthesizes one strand of the telomeric DNA using as a template a sequence contained within the RNA component of the enzyme. See Blackburn, 1992, Annu. Rev. Biochem. 61:113-129, incorporated herein by reference.
The RNA component of human telomerase has not been reported in the scientific literature to date, although human telomerase is known to synthesize telomeric repeat units with the sequence 5'-TTAGGG-3'. See Morin, 1989, Cell 59:521-529, and Morin, 1991, Nature 353:454-456, incorporated herein by reference. This knowledge has not been sufficient to enable the isolation and identification of the remainder of the nucleotide sequence of the RNA component of human telomerase. The RNA component of the telomerase enzymes of Saccharomyces cerevisiae, certain species of Tetrahymena, as well as that of other ciliates, such as Euplotes and Glaucoma, has been sequenced and reported in the scientific literature. See Singer and Gottschling, Oct. 21, 1994, Science 266:404-409; Lingner et al., 1994, Genes & Development 8:1984-1988; Greider and Blackburn, 1989, Nature 337:331-337; Romero and Blackburn, 1991, Cell 67:343-353; and Shippen-Lentz and Blackburn, 1990, Science 247:546-552, each of which is incorporated herein by reference. The telomerase enzymes of these ciliates synthesize telomeric repeat units distinct from that in humans.
There is a great need for more information about human telomerase. Despite the seemingly simple nature of the repeat units of telomeric DNA, scientists have long known that telomeres have an important biological role in maintaining chromosome structure and function. More recently, scientists have speculated that loss of telomeric DNA may act as a trigger of cellular senescence and aging and that regulation of telomerase may have important biological implications. See Harley, 1991, Mutation Research 256:271-282, incorporated herein by reference.
Methods for detecting telomerase activity, as well as for identifying compounds that regulate or affect telomerase activity, together with methods for therapy and diagnosis of cellular senescence and immortalization by controlling telomere length and telomerase activity, have also been described. See PCT patent publication No. 93/23572, published Nov. 25, 1993, and West et al., U.S. Pat. No. 5,648,215; Kim et al., U.S. Pat. No. 5,629,154; U.S. patent application 08/288,501, filed Aug. 10, 1994; West, U.S. Patent No. 5,482,838; West et al., U.S. Pat. No. 5,645,986; U.S patent application Ser. No. 08/151,477, filed Nov. 12, 1993; U.S. patent application Ser. No. 08/060,952, now U.S. Pat. No. 5,685,932 filed May 13, 1993; West et al., U.S. Pat. No. 5,489,508 and U.S. patent application Ser. No. 07/882,438, filed May 13, 1992, now abandoned, each of which is incorporated herein by reference. West et al., U.S. Pat. No. 5,489,508, hypothesized that feeding cells a synthetic TTAGGGTTAGGG (SEQ ID NO:45) oligonucleotide should competitively inhibit the ability of telomerase to elongate chromosome ends, and thus should lead to telomere shortening and senescence in cancer cells.
Significant improvements to and new opportunities for telomerase-mediated therapies and telomerase assays and screening methods could be realized if nucleic acid comprising the RNA component and/or encoding the protein components of telomerase were available in pure or isolatable form and the nucleotide sequences of such nucleic acids were known. The present invention meets these and other needs and provides such improvements and opportunities.